The present invention relates to a sliding member, particularly, having superior wear resistance, superior scuffing resistance, and a superior property not to increase an amount of wear on an opponent material (hereinafter referred as an opponent attacking property), for example used as a sliding member of an internal-combustion engine.
There have been applied conventional surface treatments such as hard chromium plating and nitriding for surfaces processing for the purpose of improving wear resistance, on a sliding surface of a piston ring as a sliding member for an internal-combustion engine in order to improve durability.
In recent years, however, since piston rings have been subjected to the increasingly harsh operating environments due to higher engine outputs and lightening of an internal-combustion engine, piston rings which are processed with the conventional surface treatments can not be satisfied a function such as wear resistance sufficiently,
For that reason, it is demanded that a sliding member such as a piston ring has a film or is applied a surface treatment, which have a superior quality such as superior wear resistance, superior scuffing resistance, and a superior opponent attacking property.
To respond to these problems, some internal-combustion engines or parts thereof are coated with a hard film such as a film of chromium nitride (Cr--N) or titanium nitride (Ti--N) which is prepared through use of a physical vapor deposition (PVD) method, in order to improved wear resistance. These films, however, have a problem such that the films make an amount of wear of a cylinder liner as an opponent material increase on occasion, although the wear resistance thereof is improved.